One process for producing a wafer such as a silicon wafer or a compound semiconductor wafer includes: a shaping step of shaping a silicon ingot etc. into a cylindrical ingot with predetermined dimensions using an outside diameter blade or a cup-shaped wheel; a slicing step of slicing the cylindrical ingot to a predetermined thickness using an inside diameter blade to form a wafer; a beveling step of beveling the outer circumference of the wafer using a beveling grindstone; and a finishing step of lapping, etching, and polishing the beveled surface of the wafer beveled in the beveling step to complete a substrate of integrated circuits.
FIG. 5(a) is a perspective view of a conventional beveling grindstone. FIG. 5(b) is a view in the direction of arrow Y in FIG. 5(a) and is an enlarged view of groove portions. In the beveling step, a beveling grindstone 100 shown in FIGS. 5(a) and 5(b) is brought into contact with the radial end face (hereinafter referred to as the outer circumferential surface) of a wafer (not shown) to grind the edge portions of the outer circumferential surface of the wafer. In the cut wafer formed in the shaping step and the slicing step so as to have predetermined dimensions, the edge portions of the outer circumferential surface of the wafer are sharp. When the wafer formed has such sharp edge portions, stress is concentrated on the edge portions of the wafer in the subsequent processing, and chips may fall off the edge portions of the wafer (chipping may occur). When such chipping occurs, the chips falling off the edge portions cause damage to the front and rear surfaces of the wafer in the subsequent processing step (the finishing step), and cracks are thereby formed, so that the yield of the semiconductor production apparatus is reduced. Therefore, it is very important to provide the beveling step of beveling the edge portions of the wafer after the shaping step and the slicing step.
The beveling grindstone 100 used in the beveling step includes a core 200 formed to have a substantially disk shape, as shown in FIG. 5(a). As shown in FIG. 5(b), a plurality of groove portions are formed on the outer circumferential surface of the core 200, and an abrasive grain layer 300 is secured to these groove portions. The abrasive grain layer 300 is formed over the entire outer circumferential surface of the core 200 and formed by securing an abrasive grain material such as diamond abrasive grains or CBN (cubic boron) abrasive grains (hereinafter referred to as diamond abrasive grains etc.) to the core 200 using a binder.
Known methods for securing diamond abrasive grains etc. to the outer circumferential surface of the core 200 include a resin bonding method, a vitrified bonding method, a metal bonding method (a sintering method), and an electrodeposition method (see Patent Literatures 1 to 6).
One known method for firmly securing diamond abrasive grains to the outer circumferential surface of the core 200 is to secure the diamond abrasive grains by brazing (see Patent Literature 7).